Core of a mascara brush



FIG. 1 illustrates an isometric view of a core of a mascara brush;

FIG. 2 is a right view thereof;

FIG. 3 is a left view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a rear view thereof;

FIG. 6 is an enlarged top view thereof; and,

FIG. 7 is an enlarged bottom view thereof.

The broken lines showing the bristles and the cylindrical features on the proximal end illustrate environmental structure that forms no part of the claimed design. 

CLAIM The ornamental design for a core of a mascara brush, as shown and described. 